Process parameters of hot melt adhesive film in seamless fitting of leather luggage

In the seamless bonding process of hot melt adhesive film for leather bags, the key parameters include temperature, pressure and time. The temperature is usually controlled in the range of 120 to 160 degrees Celsius. The specific value needs to be adjusted according to the material type of the hot melt adhesive film. The applicable temperature of polyamide adhesive film is higher, about 140 to 160 degrees Celsius, while the applicable temperature of polyurethane adhesive film is mostly 120 to 140 degrees Celsius. The pressure parameters are generally set between 0.3 and 0.8 MPa to ensure that the adhesive film can fully flow and penetrate the leather fibers while avoiding crushing the leather surface. The lamination time is usually 8 to 15 seconds, and it is necessary to ensure that the adhesive layer completely melts and wets the base material.

Before operation, the leather surface should be cleaned to remove grease and dust to improve bonding strength. The optimal thickness of the hot melt adhesive film is 0.05 to 0.15 mm. If it is too thick, it will affect the softness. If it is too thin, the adhesive force will be insufficient. In terms of equipment, it is recommended to use a flat-bed heat press or a continuous laminating machine equipped with a precise temperature control system. The temperature fluctuation must be controlled within plus or minus 3 degrees Celsius. During the cooling and shaping stage, the pressure must be kept below 80 degrees Celsius to prevent edge warping and delamination. Different leather materials such as first-layer cowhide, second-layer leather or PU synthetic leather need to adjust the process parameters accordingly, and determine the best fit conditions through sample testing.